Diversidade físico-geográfica no semiárido nordestino: unidades de paisagem na Bacia do Rio Bastiões, Ceará (Brasil)

The Brazilian semiarid region is a region with highly diverse landscapes that, due to tectonic controls associated with the action of past climates, gave rise to a complex mosaic of geomorphological forms, making this region one of the most heterogeneous, from a physical-natural point of view, within the Brazilian territory. Understanding and classifying landscape diversity, especially in drylands, is necessary for more effective territorial management and planning. From this perspective, this work aims to identify and understand the landscape units in the Bastiões River Basin (BHRB), in the south of the state of Ceará. This area is inserted in the context of the Chapada do Araripe and the Depressão Sertaneja, therefore located in an area of ​​geological and geomorphological transition, a fact that is reflected in the identified units. In this work, Landscape Units are understood as areas with characteristic relief patterns, differentiated based on their homogeneous physiographic and morphological configuration. Twelve landscape units were identified, some associated with the crystalline basement and others with sedimentary deposits. Among the units inserted in the crystalline geology, the dissected surface in ridges stands out, located in the central area of ​​the basin, and composed of an igneous lithology associated with the Campos Sales-Assaré Pluton. In the sedimentary substrate, the structural summit and the convex top stand out, supported by the fluvial sandstones of the Exu Formation. These units reflect the heterogeneity of the basin and the action of lithostructural, geomorphological and climatic controls on the morphology and dynamics of the landscape, notably distinct in the areas of crystalline and sedimentary basement.